a. Field of Invention
The invention relates generally to systems that provide for the conversion of salt water to desalination water and for the generation of electric power. More specifically, the present invention relates to systems that utilize solar energy to separate water from salt in saline water and use the resulting evaporative gases to effectively generate electric power.
b. Description of Related Art
The following patents are representative of the field pertaining to the present invention:
U.S. Pat. No. 5,727,379 to Cohn describes an electric power generation system that combines a gas turbine generator with a solar power plant and utilizes the gas turbine exhaust for steam superheating and feed water heating only. The solar heater is only utilized for boiling or evaporation of feed water into steam, the feed water having previously been heated by a downstream portion of the turbine exhaust. In order to balance the disparity between the specific heats of water and steam to thus optimize the system, the steam is superheated by and upstream portion of the turbine exhaust to first drive a high pressure steam turbine and then reheated by the same exhaust over the same temperature range to drive a low pressure steam turbine.
U.S. Pat. No. 5,405,503 to Simpson et al. describes a process and apparatus for desalinating seawater for brine and purifying water which contains minerals, salts, and other dissolved solids while simultaneously generating power. The salinous water is heated in a boiler to form steam and a concentrated brine. The concentrated brine is removed from the boiler, the steam produced in the boiler is washed with fresh water to remove trace salts and inorganic materials, and water bearing trace salts and inorganic materials are returned to the boiler. The washed steam is expanded across a turbine to generate electrical or mechanical power which is utilized as a product. The steam exhausted from the turbine is collected and condensed, and one portion of the condensed water is utilized as a fresh water product and another portion of the condensed water is used as the wash water to wash the steam produced in the boiler. Energy efficiency is improved by heat exchanging the hot concentrated brine against the salinous feed water or by flashing the brine to produce steam. Boiler scaling and corrosion may be controlled by feed water pretreatment. By utilizing distillation combined with power generation, demand for fresh water and power can be satisfied simultaneously.
U.S. Pat. No. 4,323,052 to Stark describes solar energy systems that provide for the distillation of liquids and/or the production of electricity using photovoltaic cells. Apparatus are disclosed which include an undulated system for conducting the liquid to be distilled, a linear lens disposed to concentrate solar energy on or below the undulated system, and a conduit transparent to visible light interposed between the undulated system and the linear lens. A cooling fluid is supplied to the conduit for assisting condensation of liquid evaporated from the undulated system on the lower wall of the conduit. The condensed liquid, the condensate and a concentrate of the liquid being distilled are collected. An array of photovoltaic cells may be disposed in the undulated system at a location of the concentration of solar energy to thereby provide for both distillation of the liquid and generation of electricity. Instead of an undulated system for conducting the liquid to be distilled, in one embodiment, a first transparent tube is disposed in a second transparent tube. The liquid to be distilled evaporates in the first transparent tube and is condensed on the upper wall thereof which has an outer surface in contact with the cooling fluid. If desired, photovoltaic cells may also be disposed in the first transparent tube. In another disclosed embodiment, a collector comprises tubes one disposed in the other with a fluid being circulated through each tube and insulation surrounding the lower portion of the tubes. Photovoltaic cells may be disposed in the innermost tube which is transparent.
U.S. Pat. No. 4,110,172 to Spears, Jr. describes a water-containing pond for collecting solar energy for utilization in a process for recovering potable water from non-potable water and/or for the generation of power. The solar pond in designed to increase the quantity and efficiency of water evaporation, from heated pond water, into a heated flowing air stream. Construction in such that there is afforded an increase in the absorptivity/emissivity (a/e) ratio with respect to the incidence of solar radiation.
U.S. Pat. No. 3,451,220 to Buscemi describes a combined closed-cycle condensable vapor motivated turbine power plant for generating electrical power and a liquid distillation plant for desalinating sea water, wherein the brine or feed liquid heater for the distillation plant is energized by exhaust steam from a back pressure turbine. The back pressure turbine is connected in tandem with one or more condensing turbines and the back pressure turbine and condensing turbines are fed motive vapor in parallel by a common conduit, thereby providing flexibility in control of the electrical and water production rates for varying demand. The control includes an arrangement for controlling the pressure of the heating vapor admitted to the brine heater regardless of load demand on the turbines, during periods in which water distillation requirements are constant, and in which the hot exhaust vapor supply from the back pressure turbine to the brine heater may be diverted during no load requirements on the distillation plant. The invention provides a combined plant of large output capability in which the hot vapor for motivating the turbines and the brine heater may be advantageously generated by a single nuclear reactor.
U.S. Pat. No. 3,342,697 to Hammond describes a device that constitutes a multilevel plural stage evaporator for the flash distillation of saline water, economically suited for large volume purification systems. Brine heated by a primary heat source is fed to a series of multilevel trays at one end of the evaporator shell and flows through successive stages defined by compartments formed in the common chamber of the evaporator shell at progressively lower pressures to flash and produce vapor. Condenser coils on either side of the tier of trays condense the vapor which is then collected in common troughs at the base of the shell. The feed is circulated through the condenser coils countercurrent to brine flow in the trays to serve the dual purpose of condensing the vapors and preheating the feed.
U.S. Pat. No. 2,902,028 to Manly describes a solar distillation unit comprising a recessed exteriorly insulated shell, transparent means sealing said recess to form a heating zone, a removable evaporator unit positioned in said heating zone, means positioned above the heating zone for focusing the sun's rays on the surface of said evaporator unit, feed water inlet lines in fluid communication with said heating zone located adjacent each end of said evaporator unit and including means for spraying feed water over the surface of said evaporator unit, means to tiltably mount said unit to respectively raise and lower the ends thereof, valve means operable to supply feed water to the uppermost of said feed lines when the unit is tilted at an angle, means for switching said valve to supply the water to the other of said feed lines when the angle of tilt is reversed, said evaporator unit comprising a plurality of open-ended tubes lying transverse the normal flow of water, adjacent tubes being in close proximity, means for maintaining said tubes in close proximity to form a rigid removable structure, said open-ended tubes being provided with apertures to permit a limited flow of the water cascading over said tubes into the interior thereof, a vapor outlet from the heating zone and means positioned between said heating zone and said vapor outlet for preventing flow of feed water from said heating zone into said vapor outlet.
U.S. Design Pat. No. 2,636,129 to Agnew describes a solar engine, a reservoir, a basin for receiving liquid from the reservoir, a differential pressure conduit extending from the reservoir to the basin for passing liquid into the latter, means in said conduit for removing free air in the liquid passing therethrough, a transparent dome for the basin and comprising a plurality of flat sheets for transmitting solar rays to evaporate the liquid in the basin, an upwardly directed duct extending from said dome to conduct the evaporated liquid to a level above and at a substantially lower atmospheric pressure than that of both the reservoir and the basin, a condenser at the upper end of the duct to condense said vapors, means for removing free air from the condenser, a storage reservoir elevated above the first-mentioned reservoir, and a differential pressure conduit leading from the condenser to the storage reservoir.
United States Design Patent No. 2002/0092761 A1 to Nagler describes an apparatus for the desalination or purification of water comprising a non-solid vessel having a bottom defining an opening, the vessel capable of being partially submerged below the surface of a body of water, a pan located within the vessel, the pan being flexibly connected to the inner wall of the vessel and being located beneath the surface of the water, a lens fixably connected to the top of the vessel, wherein the lens is focused beneath the surface of the water and above the surface of the pan means for varying the orientation of the vessel in accordance with the location of the sun, and means for condensing steam generated in the non-solid vessel, whereby steam generated in the non-solid vessel is condensed outside of the non-solid vessel. A method for the desalination or purification of water comprises the steps of containing a body of water within a vessel, the vessel having a lens fixably attached at the top and bottom defining an opening, located a pan just below the surface of the water, focusing the lens just beneath the surface of the water and just above the bottom surface of the pan, condensing water vapor, re-filling the vessel with water as the water is converted to steam, and periodically re-orienting the vessel in a manner that tracks movement of the sun.
Notwithstanding the prior art, the present invention is neither taught nor rendered obvious thereby.